This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. RNA metabolism requires the action of numerous ATP-dependent, molecular motor proteins that are believed to transport, remodel, and unwind secondary structures in RNA sequences. Many of these molecular motors are DEAD-box or closely related proteins. Many positive strand RNA viruses, such as the hepatitis C virus (HCV), require the activity of these proteins for RNA replication. Determination of the mechanism of these proteins and their specific functions is of fundamental importance to our understanding of viral replication as well as RNA metabolism in general. Non-structural protein 3 (NS3) is an RNA motor protein (or helicase), that is necessary for HCV replication. Our data supports the hypothesis that NS3 exists in equilibrium between monomeric and oligomeric species, and that its RNA unwinding activity increases with increasing oligomerization. Our data suggest that NS3 helicase can form filaments on RNA and DNA. We wish to establish a collaborative effort to visualize these filaments. The attached manuscripts describes some of our evidence for filament formation on DNA. However, most of the data supporting filament formation is yet to be published. We wish to establish this collaboration in order to thoroughly investigate protein-protien and protein-DNA interactions of NS3. We have no experience in EM, but are aware of numerous examples in which filament formation has been characterized by this method.